I have been trying to get my Huawei E303C 3G datacard to be working in MacBook Pro (15" retina i7 with OSX 10.8.3). Device showed a blinking green light, otherwise there was no sign of a connected USB device.

1. Downloaded Huawei Mobile Partner client for Mac
2. System preferences > Network > (checked for Huawei service), but it wasn’t there.
3. Checked for disk filesystems: $ df -h, it didn’t listed huawei device.
4. Listed all devices: $ ls /dev, and checked for tty.HUAWEIMobile-Pcui, but still it was the same. (more info)
5. Installed ‘3 connect installer’, to search seperately for Huawei device, still no presence of datacard detected. (more info)

Little green light kept on blinking, though device didn’t get detected at all. Googled and tried out even more ways, till I found out this - connect datacard via USB hub - and guess what - it worked perfectly fine! Thats one of the unexpected solutions I ever have seen!!

the problem is with MacBook Pro’s new USB ports (USB 2.0 and 3.0 integrated) and Huawei E303C Datacard. It is a hardware support issue with Huawei E303C Datacard.